Grinding machine



.Allg 9 19.32 M. MAAG ET AL 1,870,8w

GRINDING MACHINE Original Filed Nov. 10. 1928 2 She'etsuSheet 1 r I L 1Fig-2 w X" MMAAG Aug. 9, 1932.

M. MAAG ET Al.

' GRINDING MACHINE 2 Sheets-Shea?l 2l Original Filed Nov. 10. 1928 x JB' Patented Aug. 9, 1932 UNirI-:D sTATEsPATENr ori-ics MAX Mime, orSCHWAMENDINGEN, SWITZERLAND, AND ROBERT sALoMoN, or NEU-1ILLY-S'UR-SEINE, FRANCE, ASSIGNORS AFFUTER, OF PARIS,v FRANCE 'rosoorn'rnnnrunns DE MAGHINES GRINDING MAGHINE Original application 1edN'ovember 10, 1928, Serial No. 318,327, and in 'Germany November 23,1927.

' Divided and this application filed December 28, 1929. Serial No.417,051.

Our invention relates to a machine for the manufacture of knives, suchas safety razor blades, and more particularly to a bladesharpeningorgrin'ding machine designed to 5 carry out the method disclosed andclaimed in our co-pending application Ser. No.

318,327 of which the present application is a division.`

An object of our invention isa machine which will produce a razor bladehaving a perfectly sharp and acute edge and which will not inthe courseof the grinding or sharpening operation generate any ridge which wouldneccessit-ate a cumbersome treatment for removal subsequentto thegrinding operation proper. Another object of our invention .is ablade-sharpening machine of improved eliciency and accuracy ofoperation.

The process of sharpening knives, particularlyrazor blades, Which hasgenerally been in use prior to our invention, `involves the neccessityof removing the ridge from the edge after the latter has been ground.After such removal, however, d'ull spots remain on the edge independence upon the thickness of the ridge and a subsequent polishingtreatment is. required to sharpen said dull spots in order to obtain asharp edge which is ready for use. Our invention permits of materiallyreducing this polishing step which does not only involve a material timeconsumption,- but affects the curvature of the edge'fac'es in theimmediate proximity of the edge in an unfavorable manner with the resultthat the edge is less sharp than it would be with a uniform curvaturethroughout the entire 1 area of the ground faces.

Our invention permits the generation of a of the grinding operation, sothat noridge at all comes to existence during vthe sharpening process.Hence, the edge may be finished with a very slightpolishin treatmentwhich does not adversely aifect t e sensitive educ. f y

ijom the foregoing it will be appreciated that with our novel grindingmachine the sensitive edge is carefully preserved from insharp edge freefrom any ridge as a resultcarrying out our method of sharpening ra`zorjury and that the edge in case it should beinjured may be completelyre-generated in a simple manner.

Our invention is based upon the following consideration: Whena workpiece is subjected to the operation of grinding or cutting tools thelatter exert, as a rule, a pressure on the material operated upon.lfVhere they operate upon a thin edge of the work piece, the' marginalzone of said edge which on ac count of its reduced thickness islunableto re- A sist the pressure, will yield and will be pressed back from theedge to form a ridge which is no longer subjected to the tool and,therefore, is not removed. The conditions which account for theformation of aridge, are always prevailing inthe marginal zone of asharp edge, the rear faceof which is in an acute angle to the frontoperated on by the cutting or grinding tool as is the case with knivesor similar work pieces. It follows .'70

'that the -:formation of a ridge can be prevented` by providing asupport for the marginal zone which supports the latter against thepressure exerted by the tools. Our invention isbased upon the use ofsuch 75 a blade 4support; which is in intimate con 'tact with the rearface of I.the edge,'preferably throughout the entire area of the same upto the very edge, during the course of the grind'- ing process wherebyany yielding of the marginal zone and@ consequently, the formation ofany ridge is avoided. In other words, we

support the rear falce of the edge in the course of the grindingprocess, preferably over its entire length,l at least up to the linedetermining the fina-l situation of the. cutting edge of the blade so.'that ythe support is' partly ground away together with the blade bearingagainst it. In this regard our invention differs from the prior art inwhich the support no bearing against the rear face was not ground oil''together with the blade.

In the' drawings We have illustrated a pre.- 'A ferred embodiment of ournovel grinding machine which is particularly well adapted for 'ne bladesforming the subject-matter of the aforementioned application. ln Fig. 1we have shown a side view of the machine; Fig. 2 is the top viewand-Fig. 333e@ j is a perspective partial viewof the machin the partsituated to the left of line :zr-w o Fig. 1 being broken away. Fig. 4illustrates a razor blade and Fig. 5 is a diagram indicating thesuccessive stages of the method of operation.

The frame 1 is provided with a horizontal' tional engagement with theshoulder 7 and the disc 8 for common rotation.

In the recessed central part of frame 1 an auxiliary guide 12 isarranged and kept in place by means of a bolt 13 to adjustablyaccommodate a carrier 13 carrying a blade holder 17, 18, 20. The carrier13 is displaceable in longitudinal direction and may be arrested in anydesired positiopiby'means of clamping screws 14 and 14. *The ends ofcarrier 13 are formed with u wardly projecting arms having twp poin dscrews 15- and 16 inserted in axial registry. These screws servetopivotally support a block 17 and to keepl the latter in apredetermined position.

*of itsV surface may Attached to block 17 is an upwardly projectingsprln leaf 20 carrying at its upper end'a second lock 18 which isintegral with an upwardly projecting blade holder part 19 cooperatingwith another blade holder part 21 hinged to block 18 by means of a pivot22 (Fig. 3). Both blade holder parts are adapted tov keep between them arazor blade 23 such as shown in Fig. 4, and are for this purposeprovided with a bolt 51 attached to the part 19 and projecting through ahole provided in part 21 to receive a clamping nut 24. Furthermore, thepart 19 is provided with two pins 25 and 25 projecting throughregistering openings in part 21. The blade 23 is slipped with its holes52 and 52 over these pins and, then, `part 21 is folded over the bladeand pressed thereupon by the nut 24l which is applied to the bolt 51.Thus it will be seen, that the razor blade 23 is kept in uprightoperative position relative to the grinding wheel.

Furthermore, a blade support is arranged on frame 1 to bear against therear face of the edgeto support the latter. As a part of the supportingface of the support is ground away in each cycle of operation, thesupport is preferably shiftable in the direction of-its supportingfacewhereby successive portions be brought into contact relation totheblade.

' In the embodiment shown, the support is,

for this purpose, formed by a rotatable /cylin ing a shaft 28 which isparallel to shaft '6 and arranged at the same level. The shaft 28carries the cylinder 29. This cylinder has a peripheral recess 30serving to give the Agrinding disc an unobstructed and free access tothe edge of the razor blade 23, compare Fig. 4.

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Mounted on and secured to shaft 28 is a cord pulley 31 provided withclutch teeth 32 adapted to engage registering recesses in the lateralface of the supporting cylinder 29.

,The pulley is, furthermore, provided with worm gear teeth 33 engaging aworm 34 carried by a vertical shaft 46 rotatable in a suitable verticalbearing provided in the standard 26. On pulley 31 a cord 35 isfwoundhaving its one end attached thereto, at 31', and

and having its other end' hanging downwardly and provided with a weight36.

The carriage 3 is formed with a downwardly directed projection 37 whichis recessed to accomodate the end of a helical spring 38 bearing againstan adjustable screw 39 -inserted in the front'wall of frame 1 andrmitting of an adjustment ofthe pressure exerted by thespring on thecarriage 3 which is pressed towards the right and thus kept in permanentengagement with a cam 40 mounted upon a horizontal. cam shaft 41journalled in frame 1 and lcontinually subjected to a slow rotation bysuitable driving means not shown in the drawings. On this shaft a secondcam 42 is mounted having a projection 43 arranged to cti-operate with ahorizontal push rod 44'shiftably mounted in frame 1. In the course ofeach revolution of shaft 41, this push rod is once shifted towards theright thereby engaging the one arm ,of a bell crank 45 freely swingablymountedl upon the lower end of shaft 46. The other arm of the bell crank45 carries a pawl 47 arranged to engage a ratchet wheel 48rigidlyattached to shaft 46 and kept in engagement therewith by actionof a sprlng leaf 49 bearing against the pawl. The bell crank 45 is keptin perma-` nent contact with the push rod 44 by means of a tensionspring 50 vextended between a suitable projection of frame 1 and one armof the bell crank.

The operation of the machine is as follows: A rapid rotation in thedirection of the arrow of Fig. 1 is imparted to the grinding disc 8 by asuitable belt (not shown) driving the pulley 9. Simultaneously, the camshaft 41 .is slowly rotated in clockwise direction.

When the parts assume the position shown in Fig. 1 the projection 37 isin engagement with the portion of cam of smallest radius so thatcarriage Siassumes its position nearest -to, in fact in contact with,the supporting cylinder 29. In this position a cycle of operation hasjust been finished. In the course ofv the subsequent rotation of cam 40through an angle of 90 the carriage 3 ,is moved towards its uttermostleft point and the disc 8 is withdrawn from blade 23 permitting theblade holder 13 to be removed after a release of the clampng screws 14and 14 and to be replaced by a similar spare holder provided with a newblank to be sharpened.

In the course of the further rotation of cam 40 through another 90 thegrinding disc- A corresponding turn has been imparted to worm 34 and tothe supporting cylinder 29.

When the section 43 has moved past the push rod 44 the latter and thebell crank are restored to their normal position by action of thetension spring 50. The purpose of the turnoi the cylinder 29 preparatoryto a new cycle will be later explained.

In the course of the rotation of cam 40 through the third quarter of'arevolution the carriage 3 is gradually advanced towards the support 3()and the new razor blade in cont-act therewith until thelatter is engagedby the grinding disc 8 and is sharpened by the latter transformed into anearly iinished condition requiring but a. slight polishing treatment,whereupon aV new cycle of operation is initiated.

In order' to reset the grinding machine for the subsequent operation,the blade holder 13 is removed upon a suiiicient release of tneclampingscrews 14 and 14u and is replaced by a spare blade holder which containsa new blank and is Xed in place by re-tightening the screws or bolts 14and 14. This replacement of the blade holder is to be effected duringthe period of the return of the carriage 3 toward its left endpositionunder action of the cam 40 which is driven at so low a speed aswill afford the time required for such replacement.

'In Fig. 5 we have diagrammatically illustrated the successive stagesofthe operation.

-In this iigure the reference numeral 8 designates the grinding disc andI to V designate live successive positions of the grinding disc assumedin the course from its outermost position I to its innermost position Vin which the advance is ,completed ,and another cycle 'of operation isstarted. 23/illustrates a razor blade, the finished profile of which isconfined by the corner points-A, N, L, D, E while the original form ofthe blank as it is inserted in the blade holder, is indicated by thepoint-s A, B, C, D, E. It will be observed that the blank is formed by ablade having a finished back C, D, E, and an unfinished front A, B whichis to be ground to produce the front'face N, L of the edge. 29 is ,thesupporting cylinder, the peripheral face of which serves to support therear face of the edge and, for this purpose, is kept in intimate Contacttherewith and stationary thereto during the grindin process.

As heretofore mentioned, the supporting cylinder is provided with aperipheral recess extending between the points K, L, Fig. 5. This recessis increased in vcircumferential length vin the course of the operationon account of the stepwise turn imparted to thc support 29. Its`original shape is desigv until the edge L was situated in the centralplane l? of the razor blade so that a portion K, I, O, K was cut out ofthe cylinder. When' subsequently to each cycle the supporting cylinderis turned through the angle y a, the recess K, L is successivelyenlarged as each time another section G, I-I, L is cut out of thecircumference until eventually the entire cylinder is'used up and a newcylinder of the prescribed diameter must be substituted. The depth QR ofpenetration of the grinding disc 8 depends on the edge angle i 2 a ofthe razor blade which is to be produced. The larger this angle is to bemade, the lower arranged must be the blade 23 with regard to the line S,T connecting the centers of the supporting cylinder 29 and grinding disc8, and the 'more towards the right will be positioned the blade so thatthe grinding disc will deeper cut into the supporting cylinder 29 untilthe razor blade edge is situated in the central plane P.

When the grinding disc 8 approaches the positlon I onitswaytoward'the'supporting cylinder 29 a blank having its front inunfinished condition has been substituted for Y the/razor blade inishedin the preceeding cycle. 'As soon as the position II has been reachedthe grindingv process proper commences, the edge B of the blade beingprogressively cut away until the position III has been reached where theportion designated by the letters B, F, G, has been ground off.'

' on account of small di erences in shape, the

^ razor blade gradually approaches t cross-sectional profile with thepoints C and D on different sidesof the lcentral plane has been chosen.

While the grinding disc advances from as pjosition III to theposition'IV, the portion F, M, G is cut away so that the edeofthe G.where it arrives at the time IV. During this period, however, the edge Cfreely extends through the space its back lacking any supportwhatsoever, so that a ridge of the width C, G will be formed. This ridgerepresents the rim leaf which yields un Ver the pressureof thegrinding'dise and is bent out of the way of the latter on account of itsreduced thickness and' tenderness.` In the moment, however, position IVis reached, the grinding disc beginsA to operate upon a marginal zoneconned by the edge G of the razor blade which is supported by portion G,C D of the supporting cylinder 29 and, for t is reason, cannot yield tothe grinding ressure. Consequently, the advancing grin ing disc engagesfthe root of the ridge leaf'which is' bearing against the supportingcylinder 29 and as a result of the frictional engagement with thegrinding disc is abruptly torn off.

While the grinding disc advances from IV to V it exerts a unitarygrinding action on the supporting cylinder and the` razor bladesimultaneously cuttinglaway the portions G,

M, N, L of the blade and G, H, L, of the supporting cylinder. In thecourse of this stage ofthe grinding rocess the edge gradually advancesfrom y to L and, in this phase, another ridge cannot be formed becausethe edge is continually supported while it is subjected to the Igrindingpressure. LHence, it will appear that as soon as, or even before, thepoint L is reached, the edge will be perfectly sharp and free from anyridge so that any subsequent treatmentof the razor blade with a view toremoving a ridge is rendered superfluous.

The faces NL and LD are truly concave in the immediate proximity of theedge and are thereby distinguished` from the razor blades produced byknown methods in which the edge is deformed by bending stresses andsubjected to a polishing treatment which removes V material near theedge and thereby distorts `thelground concave face transforming it in4theimmediate proximity of the edgeinto a Y c p v of heat or bymechanical stresses exerted by the polishing tool.

It might be suggested that it would appear sufficient to' turn thesupporting cylinder 29, preparatory to the grindin phase, with the edgeof its recess up to 51e point L only rather than up to the point Ginasmuch asl the ridgelis removed in the moment the contact of thesupporting cylinder and the grinding disc occurs, which' occurrencemiglht just y as well be ostponed until the ed e as advanced to In thiscase a simp e support having the form of a simple plate of the profilevU, V, L, W, Y would do as this plate would not be consumed and, for thisreason, would not necessitate anyl replacement. It is to be observed,however, that in this case the operation would be finished in the momentthe ridge leaf is torn away. This tearing pif,

however, always occasions small irregularities and 'recesses on the edgeso thatthe `latter does not comply with the requirements of. e uttermostexactitude and does not satisfy the demands for a perfect razor blade.

Besides, the unavoidable wear ofthe grinding disc accounts for a certainirregularity of the final position of the razor blade ed` e which,accordingly, does not always exact y coincide with point L of thesupporting cylinder. It follows that, while a perfect grinding disccould perhaps be adjusted to always exactly reach the position V.thereby removing the rid e even with a simple support plate U, V, W, Y,under ordinary conditions,'for instance with a worn grinding disc, theposition V would sometimes not exactly be reached so that a ridge leafwould be left. For this reason we advance the grinding disc beyond theposition IV thereby cutting into the support-29. This operationcompensates for the unavoidable small deviations in the reasonablerequirements regarding the exactness of the elements of the machine, toprovide, as it were, a safety coeiicient with regard to the supportingaction, in that we support the rear face of the edge beyond the point Lmarkin the final location of the finished cutting e ge, and in that weartially cut away'thls sulpported Zone toget er with its support wh' elthe grinding disc,v appreaches its innermost position. VThe'portion ofthe support cut away in each cycle must, of

course, be replaced preparatory to the sitbsequent cycle. -l f By themachine heretofore described a cutting edge is obtained which is sharpand without any ridge, regardless of whether or not the elements of themachine operate quite accurately and whether the final edge exactlycoincides with the point L in the central plane P.

Obviously, the requirement of replacing the cut-away portion ofthesupport prior to every cycle may be complied with in a great variety ofconstructions. We prefer, however, to use `a supporting cylinder such asheretofore described as in this manner the replacement after each cyclemay be accomplished in an extremely simple manner by turning thecylinder until its edge confining the recess has been moved beyond thelocation of the iinal blade edge by such an amount as safety compensatesfor the eiects of possible inaccuracies of the machine.

ln producing the rear :tace C, D of the razor blade a similar method ofsupporting the back of the blade need not be employed, it beingsuiiicienta to support the original blank having the profile A, B, Z, Eby a small support blade Z, A', B', C', as in this case theconfiguration of the edge D is without any' consequence so that theformation of a ridge does not matter. The function of the sup-` port inthis case would simply be to prevent the blade which is given theprofile ANDZE from being sprungr out of shape. It may be mentioned thatthis preparatory stage does notv form part of our invention and that theproiile ANDZE may be produced in any suitable manner before the blade issharpened with our novel machine.

An essential requirement for the eicient operation of our machine is anintimate contact of the supporting cylinder .with the rear face of theblade edge or at least with the zone confined by the inal edge. In orderto avoid unreasonable requirements regarding the accuracy of theadjustment of the blade holder, the latter is preferably of yieldingproperties. In the embodiment shown for instance, it includes in itsstructure a spring leaf` 20 permitting 4a small lexion vertical to itsplane as well as a small turn about its vertical axis.

ln adjusting the blade, we first align the blade edge inthe desiredlevel parallel to the axis of the supnortingcylinder and, subsequently.somewhat release one of the pointed screws 15 or 16, whereupon we turnthe en- -tire blade holder about the axis 15. 16 to bring the blade infull contact .with the supporting cylinder. Then, the released pointedscrew is tightened again so as lto arrest the sure while the spring leaf20 is slightly bent.

to produce such pressure. This will also be the case, ifblades of aslightly diierentsize are inserted as the iexibility of the spring leaf20 compensates for small dierences between the shape .of the individualblades. The blade holder, however,. will be subject to small deviationsfrom its vertical position.

If it stands forwardly inclined with regard to v its normal position,the pointl D of the rear face is. liable to come intol contact with theperiphery of the supportin cylinder instead of the point G so that thenal edge would not be supported. This may obviously be avoided bydimensioning the radius of the supporting cylinder slightly smaller thanthe radius of the curvature of the porfile section C, E or,

in other words, thanthe radius of the grinding disc employed inproducing the rear face of the blade. In this manner, of course, aperfect contact over the entire surface of the rear face C, D isobviated, buty an ecient support of that zone is secured in which thefinal edge is situated and this is what counts; In dimensioning thediameter of the supporting cylinder unavoidable inaccuracies anddifferences of the individual blades are to be taken in consideration.The diameter must which would permit of such a rotation unlessparticular precautins were'taken. Any turn of the supporting cylinderduring its engagement with -the grinding disc, however, would cause thelatter to jam or perhaps even to crack. For this reason, means must beprovided which obviate a back-lash in the driving gear of the supportingcylinder. This `may be achieved in the simplest manner by causing thedriving members to be in permanent contact with'each -other in a sensecontrary to their driving effect. For this purpose we have provided theweight 36 which subjects shaft 28 to a torque of the same sense as thatproduced by the engaging grinding disk. This torque causes the teeth ofthe worm gear 33 to keep contact with the thread of the self-lockingworm 34 whereby the supporting cylinder is prevented from being turnedby the grinding disc. It follows that the advance ,of the supportingcylinder through the anglesla is, exactly speaking, performed by action.of the weight 36 rather than by the worm gear 34, 33 which really merelydetermines the exact degree of such advance.

What we claim is:

1. A blade sharpening machine comprising 4 a grinding element, asupport, a blade holder viat of said: support lis. ground off in thecourse of to keep a blade therebetween in grinding position and incontact with said support, the latter being adapted Ito be keptstationary during the grinding cycle and to be advanced betweensuccessive cycles in the direction of its supporting face wherebysuccessive portions of its surfacepmay be brought into contact relationto said blade for successive cycles of operation.

2. In a blade sharpening machine, the combination comprising abladesupport, a rotating grinding wheel, means to move the Wheel towardssaid support to such an extent that a portion of the vsupport is groundaway, and a blade holder associated with said support to keep a bladestationary relative to said support and in intimate contact with theportion cut away,.while the blade is being ground.

3.- In a blade sharpening machine, the combination comprising a bladesupport, a rotating grinding wheel, means to reciprocate said wheel toand from said blade support, means associated with the support toadvance the support step by step into the path `of saidgrinding wheel inslynchronism with the reciprocation of theisame, whereby a portione'aehstroke vjofsaid grinding Wheel, and a blade holder adapted to keepa blade stationary relative to said support and with its rear marginalzone in intimate contact withsaid portion for the purpose of subjectingits front to the action of said grinding wheel' while its edge issupported by4 said portion. 4. A blade sharpening machine comprising aframe, a carriage slidably arranged thereon, a rotating grinding discmounted on said carriage and having its axis transverse to the directionof movement of said carriage, a blade-supporting cylinder mounted Yousaid frame in opposition to said grinding disc and having its axisparallel to the axis of said disc, means to reciprocate said carriage tocause said grinding ldisc to cut into said cylinder, and a blade holderarranged between said disc and said cylinder and adapted to keep a bladein upright position with its mar-v ginal portion in contact with saidcylinder and in the path of said disc.

5. A blade sliarpening machine comprising a frame, a carriage slidablyarrangedthereon, a rotating grinding disc mounted on said carriage andhaving its axis transverse to the path of said carriage, ablade-supporting cylinder mounted on said frame in opposition to saidgrinding disc and having itaxis parallel to the axis of said disc, meansto reciprocate said carriage to cause said grinding disc to cut intosaid cylinder, means to turn said cylinder about its axis through adefinite angle, once at each reciprocation of said carriage, and a bladeholder arranged betweensaid disc and said cylinder and adapted to keep ablade in upright position with its marginal portion in contact with saidcylinder and in the path of said disc.'

6. The combination set forth in claim 4, in which said blade holdercomprises an upright spring leaf and al clamping device attachedtomovement being suiiicient for said grinding wlieel to cut into saidportion while sharpening the supported edge of the blade, means to mountsaid support for a movement which will bring another portion of it intocontacting relation with a blade after said firstmentioned portion. hasbeen ground off, and

l0 the upper end thereof and adapted to receive means for maintainingsaid support in posiv tion relative to said grinding wheel against thegrinding pressure exerted by thelatter.

. 8. In a blade Ysharpening machine, the combination comprising bladesupporting means ofnon-resilient and non-abrasive material, a rotatinggrinding wheel, means for reciprocating said wheel in the direction toand from said supporting means, means asso- *ciated with said supportingmeans for intermittently advancing said supporting means into the pathof' said grinding wheel in synchronism with the reciprocation of thesame, whereby a portion of said supporting means will be ground o in thecourse of each forward stroke of said grinding wheel, and a lbladeholder adapted to keep a blade stationary relative' to said support andwith its one marginal face in intimate contact with said portion for thepurpose of subjecting its other marginal face to the action of saidgrinding wheel while the very edge of the blade is supported by saidportion.

9.- A blade sharpening machine comprising a,frame,-a carriage slidablyarranged thereon, a rotating grinding disc mounted on said carriage andhaving its axis. horizontal and transverse to said carriage, a

blade' supporting body of non-abrasive and non-resilientmaterial'mounted on said frame 1n opposition to said grinding disc,means to reciprocate said carriage to cause saidgrinding disc to cutinto said body, and a vblade holder arrangedbetween said disc and saidbody and adapted to keep a blade inA upright position with its marginalportion in contact with said body and in the path of saiddisc to beground off simultaneously with -said body.

10. In -a blade sharpening.` machine, the

combination comprising a non-resilient and non-.abraslve support havinga rectilinear portion dlmensloned to support the marginal face of a.razor blade along its entire edge, a bladeholder associated therewith tokeep a blade stationary relative to, and in intimate Contact with saidportion of the support, agrnding wheel and means to move said wheeltowardssaid support and said blade such a distance that contactingportions of the blade and said support are snlultaneously ground away.

In testimony whereof we alix our signatures.

MAX MAAG. ROBERT SALOMON.

